Chef Notes from Kris Hammond’s chapter in ICBR
Planning as Remembering • What did you do the last time you wrote a program? • What does an architect do?
What to remember • Successes • Failures • Goals • The plan
“New theory of planning” • Search memory for plans that satisfy many goals • Learn when recovering from errors • Keep old plans around for reuse
Plan indexes • Successes and Failures • “The case based approach to finding an initial plan is to anticipate problems so the planner can find plans that avoid them” • Anticipate and avoid vs. create and debug
Debugging still required • Mistakes as expectation failures rather than planning failures. • Debugging as explanation; • Repair as plan repair and knowledge repair.
Learning/Adaptation • Learn new plans that avoid problems • New Features that predict problems • Learn the repairs
Plan retriever • “Best match” • Plan memory • Goal similarity metric • Goal value hierarchy
Plan modification • Modification rules • Knowledge critics • General plan knowledge
Plan Storer • Index under same goals as retriever will find them (natch)
Plan Repair • Knowledge of plan+fault to new plan • Knowledge of planning language • Side-effects, benefits, etc. • Causal knowledge • Explanation used to “learn from failure” (blame assignment)
Example: Recipe • Goals: Beef, broccoli stir-fry • Retrieve: beef+green-beans • Alter: • replace green-beans with broccoli • Chop broccoli first • Predicted goals: tender beef, savory dish, crisp broccoli, salty dish, sweet dish, garlicky dish • Cook • Failure! Broccoli is soggy
Failure explanation • What’s wrong? • Broccoli soggy, not crisp • What led to this? • Liquid in pan from beef • Why did you do this? • To cook beef
Plan repair strategies • Concurrent plans sometimes disable one another’s preconditions • Possible plans • Split-and-reform (multiple steps) • Alter-plan:side-effect (replace step with new plan) • Adjunct-plan (add new step)
New plan! • From ‘stir fry broccoli beef, broccoli, garlic, soysauce, sugar’to: • Stir fry broccoli • Stir fry rest • Add ingredients together
Anticipating failure • Broccoli-like veggies will cause this failure in the future • Eg. Looking for a recipe for stir-fried chicken and snow-peas.